A team of United States National Institute of Aging (NIA) investigators has identified characteristics of the microbiome that change with age and may contribute to age-related disease.

The findings, published in Nature Aging, suggest that the skin microbiome in particular may be especially important in understanding age-related health conditions.

The microbiome is the collection of all microbes, such as bacteria, fungi, and viruses, that live on the inside and outside of our bodies. Some microbes are helpful, protecting from infection and other diseases, while others can be harmful. Previous research has linked changes in the microbiome to conditions related to ageing, including heart disease, cancer, and infection. A better understanding of how the microbiome changes with age may help scientists develop interventions to improve quality of life for older adults. To this end, a team of University of Connecticut and Jackson Laboratory researchers in the US conducted a study to examine the relationship between the microbiome, ageing, and age-related health conditions.

The scientists collected skin, mouth, and gut microbiome samples from younger adults, older adults living at home, and older adults living in nursing homes. Simultaneously, they assessed the frailty of the participants and garnered data about their medical history, diet, and hygiene. The team used advanced genomic sequencing techniques to identify and classify the complex microbial communities found on each participant’s body.

They found many different relationships between specific microbes, ageing, and age-related conditions, with the most dramatic differences between the three groups of people being related to the skin microbiome. While none of the microbes were consistently associated with chronological age, they found correlations between frailty and several microbes at specific skin sites. Some microbes were associated with greater presence of frailty and others were associated with a lower presence of frailty.

Another key finding was that older adults had less Cutibacterium acnes on their skin than younger adults. Cutibacterium acnes — the same bacteria that causes acne — is abundant on healthy skin and protects against harmful microbes. The researchers hypothesise that the loss of Cutibacterium acnes may contribute to older adults’ increased risk of infection. More specifically, the older adults living in nursing homes had more coagulase negative staphylococci, a type of bacteria that is a major cause of infections, than both older adults living at home and younger adults.

The scientists noted several limitations to their study, namely that the group of older adults living in nursing homes was frailer, predominantly female, and had higher body mass indexes than the other groups, which may have affected their results. Because many of the relationships the researchers found involved microbes on the skin, they believe that the skin microbiome may be especially important to ageing and age-related health conditions. Still, the study provides a foundation for future research and establishes the microbiome as a possible target for treatments and strategies to prevent age-related health conditions.

Source: National Institute on Aging